Up to now, the fuel control twist grip of a scooter or similar vehicle has always been manufactured in a single piece, covered, on the outside, with a rubber or similar grip, for secure gripping on the part of the driver, and connected, in the part facing the handlebar, with flexible transmission means connected to the carburettor and supported in the handlebar by a tubular support element at the end of which the fuel control twist grip is usually located.
All anti-theft devices up to now designed for and applied to scooters or motorvehicles in general, have been designed to control the possibility of manoeuvring and turning the handlebar around the steering axis or on the electrical power supply to the motor. These types of anti-theft device have proved to be quite inefficient, since they can easily be overcome.
Another type of anti-theft device in use is that which uses mechanical means for blocking the wheel(s), or again the handlebar, in the form of chains or rigid shackle-type locks which are fitted with suitable safety locks. This type of anti-theft device has demonstrated greater resistance to braking or cutting, but still relies on a lock which can be broken and is awkward and inconvenient to carry around and to apply.
Still another type of anti-theft device disclosed in the French patent FR-A-1 132 662 and in the French patent application FR-A-2 598 995 comprises a lock co-axially disposed inside the fuel control twist grip and capable of blocking the rotation of the twist grip by making the twist grip coupled to the handlebar of the motorvehicle. However, also this type of anti-theft device relies on the lock which can be broken.